Rotary machine heat sink

ABSTRACT

A heat sink that can be positioned around a rotating shaft includes a cylindrical body with a first end and a second end, a bore running through the body with a first opening at the first end of the body and a second opening at the second end of the body, fins extending radially outward from the body and running from the first end to the second end of the body, and channels defined between the fins and running from the first end to the second end of the body.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority to U.S. provisional application Ser.No. 14/293,461, filed on Jun. 2, 2014, and entitled “Rotary Machine HeatSink,” the disclosure of which is incorporated by reference in itsentirety.

BACKGROUND

The present invention relates to rotary machines, and in particular, toa heat sink for a bearing in an air cycle machine.

Air cycle machines are used in environmental control systems in aircraftto condition air for delivery to an aircraft cabin. Conditioned air isair at a temperature, pressure, and humidity desirable for aircraftpassenger comfort and safety. At or near ground level, the ambient airtemperature and/or humidity is often sufficiently high that the air mustbe cooled as part of the conditioning process before being delivered tothe aircraft cabin. At flight altitude, ambient air is often far coolerthan desired, but at such a low pressure that it must be compressed toan acceptable pressure as part of the conditioning process. Compressingambient air at flight altitude heats the resulting pressured airsufficiently that it must be cooled, even if the ambient air temperatureis very low. Thus, under most conditions, heat must be removed from airby the air cycle machine before the air is delivered to the aircraftcabin.

To condition the air as needed, air cycle machines include a fansection, a compressor section, and a turbine section that are allmounted on a common shaft. The compressor receives partially compressedair from the aircraft and further compresses the air. The compressed airthen moves through a heat exchanger and is cooled by the fan section.The air then moves through the turbine section where it is expanded foruse in the aircraft, for example, for use as cabin air. The turbinesection also extracts energy from the air and uses the energy to drivethe fan section and the compressor section via the common shaft.

Air cycle machines also include bearings that are positioned around thecommon shaft. The bearings are cooled by passing a cooling air flowthrough a cavity that is adjacent the bearing. The cooling air flow thenexits the cavity and is discharged from the air cycle machine into anambient. The cooling air flow is limited in that it can only cool thebearing using convective heat transfer. The cooling air flow is furtherlimited in that the cooling air flow in the cavity flows through acenter of the cavity, meaning a majority of the cooling air flow doesnot flow across a surface of the bearing.

SUMMARY

A heat sink that can be positioned around a rotating shaft includes acylindrical body with a first end and a second end. A bore runs throughthe body with a first opening at the first end of the body and a secondopening at the second end of the body. Fins extend radially outward fromthe body and run from the first end to the second end of the body.Channels are defined between the fins and run from the first end to thesecond end of the body.

A rotary machine includes a shaft extending through the rotary machineand a bearing positioned around the shaft. A heat sink is mounted on theshaft between the bearing and the shaft. The heat sink has a cylindricalbody with fins extending radially outward from the body and running froma first end to a second end of the body.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an air cycle machine.

FIG. 2A is a perspective view of a heat sink.

FIG. 2B is a cross-sectional side view of the heat sink seen in FIG. 2A.

FIG. 3 is an enlarged cross-sectional view of the heat sink in a fansection of the air cycle machine.

DETAILED DESCRIPTION

In general, the present disclosure is a heat sink for use in a rotarymachine. The heat sink can be mounted on a shaft between a bearing andthe shaft to dissipate heat away from the bearing and out of the rotarymachine. The heat sink includes a body with a bore running through thebody from a first end to a second end. A shaft can be positioned in thebore. A plurality of fins extend radially outward from the body and runfrom the first end to the second end of the body. Each of the pluralityof fins includes a contact surface that can be positioned against aninner surface of the bearing to conductively transfer heat away from thebearing. A plurality of channels are defined between the plurality offins and run from the first end to the second end of the body. Coolingair flow can flow through the plurality of channels and across the innersurface of the bearing to convectively transfer heat away from thebearing. Allowing for both conductive and convective heat transfer makethe heat sink an efficient and effective way to transfer heat away fromthe bearing and out of the rotary machine.

FIG. 1 is a cross-sectional view of air cycle machine 10. Air cyclemachine 10 includes fan section 12, compressor section 14, and turbinesection 16 that are all mounted on shaft 18. Shaft 18 rotates aroundcentral axis 20. Fan section 12 includes fan blade 30. Compressorsection 14 includes compressor inlet 40, compressor outlet 42, andcompressor nozzle 44. Turbine section 16 includes turbine inlet 50,turbine outlet 52, and turbine nozzle 54. Also shown in FIG. 1 is heatexchanger 60, housing 70, bearing 72, bearing sleeve 74, bearing foil76, bearing journal 78, cooling air flow 80, cooling air flow inlet 82,cavity 84, opening 86, and heat sink 100.

Shaft 18 is a rod, such as a titanium tie-rod, used to connect othercomponents of air cycle machine 10. Central axis 20 is an axis withrespect to which other components may be arranged.

Fan section 12 includes fan blade 30. Fan section 12 is mounted on shaft18. Fan blades 30 rotate around shaft 18. Fan section 12 is typicallyused to draw in ram air from an associated gas turbine engine or otheraircraft component. Fan section 12 may also be used to draw air throughheat exchanger 60.

Compressor section 14 includes compressor inlet 40, compressor outlet42, and compressor nozzle 44. Compressor section 14 is mounted on shaft18. Compressor inlet 40 is a duct through which air is received to becompressed. Compressor outlet 42 is a duct through which air can berouted to other systems after it has been compressed in compressorsection 14. Compressor nozzle 44 is a nozzle section that rotatesthrough the air in compressor section 14. In particular, compressornozzle 44 is a rotor or impeller.

Turbine section 16 includes turbine inlet 50, turbine outlet 52, andturbine nozzle 54. Turbine section 16 is mounted on shaft 18. Turbineinlet 50 is a duct through which air passes prior to expansion inturbine section 16. Turbine outlet 52 is a duct through which air can berouted after it has been expanded to be used in other areas on anaircraft. For example, air can be routed out of turbine outlet 52 andinto a cabin for use as cabin air. Turbine nozzle 54 is a nozzle sectionthat extracts energy from air passing through turbine section 16. Inparticular, turbine nozzle 54 is a rotor or impeller. Air passingthrough turbine section 16 drives the rotation of turbine section 16 andany attached components, including shaft 18, fan section 12, andcompressor section 14.

Air is received in air cycle machine 10 at compressor inlet 40. The aircan be ram air from a ram air scoop or the air can be pulled into aircycle 10 using fan section 12 from an associated gas turbine or otheraircraft component. The air passes through compressor section 14 whereit is compressed with compressor nozzle 44 and then discharged out ofcompressor outlet 42. From compressor outlet 42, the air can passthrough heat exchanger 60. Fan section 12 may be used to draw airthrough heat exchanger 60. Air that exits heat exchanger 60 is thenrouted into turbine inlet 50. The air expands as it passes throughturbine section 16 and it drives turbine nozzle 54 before it isdischarged out of turbine outlet 52. Air that is discharged out ofturbine outlet 52 can then be routed to other parts of the aircraft, forexample, for use as cabin air.

Adjacent fan section 12 in air cycle machine 10 is housing 70. Housing70 forms an outer portion of air cycle machine 10. Bearing 72 ispositioned between shaft 18 and housing 70. Bearing 72 is a foil bearingin the embodiment shown in FIG. 1. Bearing 72 includes bearing sleeve74, bearing foil 76, and bearing journal 78. Bearing foil 76 ispositioned between bearing sleeve 74 and bearing journal 78. Bearingsleeve 74 forms an outer surface of bearing 72 and bearing journal 78forms an inner surface of bearing 72. The inner surface of bearingjournal 78 faces shaft 18. Heat sink 100 is mounted on shaft 18 betweenbearing 72 and shaft 18 to dissipate heat out of bearing 72.

Cooling air flow 80 is bled from the air being routed from heatexchanger 60 to turbine inlet 50. Cooling air flow 80 is routed throughcooling air flow inlet 82 and through air cycle machine 10 to cavity 84.Cavity 84 is an open area surrounding shaft 18 that is defined by fansection 12 and turbine section 16. Heat sink 100 is positioned in cavity84 adjacent fan blade 30. Cooling air flow 80 will flow through cavity84 and will pass through heat sink 100 to cool bearing 72. Cooling airflow 80 will then exit through opening 86 that is formed between housing70 and fan blade 30 and will be discharged into an ambient out of aircycle machine 10.

FIG. 2A is a perspective view of heat sink 100. FIG. 2B is across-sectional side view of heat sink 100. Heat sink 100 includes body102, bore 104, fins 106, channels 108, standoffs 110, and contactsurfaces 112.

Heat sink 100 includes cylindrical body 102. Heat sink 100 is made outof a metallic material. Bore 104 extends axially through body 102 with afirst opening at a first end of body 102 and a second opening at asecond end of body 102. Bore 104 runs through heat sink 100 so that ashaft or other part can be positioned in bore 104 of heat sink 100.

Fins 106 extend radially outward from body 102 and run from the firstend to the second end of body 102. Fins 106 each have contact surface112 on a radially outer surface of fins 106. Contact surfaces 112 cancome into contact with a hot part to dissipate heat out of the hot partand into fins 106. Channels 108 are defined in between fins 106 and runfrom the first end to the second end of body 102. Channels 108 are openspaces in between fins 106 through which air can flow.

Standoffs 110 are protrusions that are positioned on a first end and asecond end of body 102 of heat sink 100. In the embodiment shown in FIG.2A, there are two standoffs 110 positioned on each end of heat sink 100.In alternate embodiments, any number of standoffs 110 can be positionedon the first end and the second end of body 102 of heat sink 100.Standoffs 110 are positioned on heat sink 100 to limit axial movement ofheat sink 100 with respect to shaft 18. If heat sink 100 were to slideaxially forward or aft, standoffs 110 would come into contact withadjacent components and limit the axial movement of heat sink 100.

Heat sink 100 can be used in any rotary machine that has a shaft and abearing positioned around the shaft. This can include air cycle machinesand other turbine and motor driven compressors and fans. Heat sink 100is advantageous, as heat can be transferred conductively andconvectively through heat sink 100. Heat is transferred conductivelywhen contact surfaces 112 of fins 106 come into contact with a hot partand absorb heat from the hot part into heat sink 100. Heat istransferred convectively as cooling air flow in channels 108 flowsacross a surface of a hot part and absorbs heat from the hot part intothe cooling air flow.

FIG. 3 is an enlarged cross-sectional view of heat sink 100 in fansection 12 of air cycle machine 10. The portion of air cycle machine 10shown in FIG. 3 includes fan section 12 (including fan blade 30), shaft18, housing 70, bearing 72, bearing sleeve 74, bearing foil 76, bearingjournal 78, cavity 84, opening 86, and heat sink 100. Heat sink 100further includes body 102, fins 106, channels 108, standoffs 110, andcontact surfaces 112.

Air cycle machine 10 includes fan section 12 that is mounted on shaft18. Shaft 18 is a common shaft that runs through air cycle machine 10and that rotates around central axis 20. Fan section 12 includes fanblade 30 that rotates with shaft 18 around central axis 20. Adjacent fanblade 30 is housing 70. Housing 70 forms an outer portion of air cyclemachine 10.

Positioned between shaft 18 and housing 70 is bearing 72. Bearing 72 isa foil bearing that includes bearing sleeve 74, bearing foil 76, andbearing journal 78. Bearing foil 76 is positioned between bearing sleeve74 and bearing journal 78. Bearing sleeve 74 forms an outer surface ofbearing 72 and bearing journal 78 forms an inner surface of bearing 72.The inner surface of bearing journal 78 faces shaft 18. Cavity 84 isformed between shaft 18 and the inner surface of bearing journal 78.Cooling air flow can be routed through cavity 84 to cool bearing 72. Thecooling air flow can then exit through opening 86. Opening 86 is anopening through bearing journal 78 between fan blade 30 and housing 70.After cooling air flows through opening 86 it can be discharged from aircycle machine 10 into an ambient.

Positioned in cavity 84 around shaft 18 is heat sink 100. Heat sink 100is mounted on shaft 18 so that it rotates with shaft 18 around centralaxis 20. Heat sink 100 includes body 102 with fins 106 extendingradially outward from body 102. Each of fins 106 includes contactsurface 112 on a radially outer surface that comes into contact with theinner surface of journal bearing 68. Channels 108 extend between fins106 and are shown in phantom in FIG. 3. The cooling air flow that flowsthrough cavity 84 is forced to flow through channels 108.

Heat sink 100 also includes standoffs 110, which are positioned to keepheat sink 100 in place in air cycle machine 10. If heat sink 100 were toslide on shaft 18 in an axially forward or aft direction, the first endor the second end of channels 108 may abut a solid surface surroundingcavity 84. This could prevent the cooling air flow from flowing throughchannels 108 and out of opening 86, and could choke the cooling air flowin cavity 84. Standoffs 110 prevent this from happening by preventingchannels 108 on heat sink 100 from abutting a solid surface. If heatsink 100 were to move in a forward direction, standoff 110 on the firstend of heat sink 100 would abut the disk or hub portion of fan blade 30.If heat sink 100 were to move in an aft direction, standoff 110 on thesecond end of heat sink 100 would abut a shoulder of bearing journal 78.

Heat sink 100 transfers heat out of bearing 72 and into an ambient intwo ways. First, heat can be transferred through bearing journal 78 intofins 106 of heat sink 100 through contact surfaces 112. This isconductive heat transfer between two abutting surfaces. Heat that istransferred into fins 106 can then be dissipated through heat sink 100and into shaft 18. Heat in shaft 18 can transfer through shaft 18 andcan be dissipated into an ambient. Second, heat can be transferredthrough bearing journal 78 and into the cooling air flow that is flowingthrough channels 108 of heat sink 100. This is convective heat transfer,as heat is being transferred into air that is flowing across the innersurface of bearing journal 78. The cooling air flow that is flowingthrough channels 108 flows through opening 86 where it is discharged outof air cycle machine 10. This discharges heat from bearing 72 into anambient through the cooling air flow.

In prior art systems, bearing 72 was cooled by flowing air throughcavity 84. This cooling method was inefficient, as cooling air that wasflowing through cavity 84 had a large area through which it was flowing.A majority of the cooling air flowed through the center of cavity 84between shaft 18 and journal bearing 68. This made the cooling methodinefficient, as a majority of the cooling air was not coming intocontact with the inner surface of bearing journal 78.

Heat sink 100 is advantageous over prior art cooling systems, as heatcan be transferred out of bearing journal 78 with both conductive andconvective heat transfer. The conductive heat transfer takes placebetween fins 106 and the inner surface of bearing journal 78. Theconvective heat transfer takes place between the cooling air flowingthrough channels 108 and the inner surface of bearing journal 78. Theconvective heat transfer that happens with heat sink 100 is furtheradvantageous over prior art convective heat transfer, as the cooling airflow is forced to flow across the inner surface of bearing journal 78when it flows through channels 108. This increase the effectiveness andefficiency of the convective heat transfer than was previously possible,as more cooling air flow is coming into contact with the inner surfaceof bearing journal 78. Heat sink 100 thus improves the cooling ofbearing 72 to make bearing 72 more reliable.

Heat sink 100 also provides several advantages for air cycle machine 10.First, heat sink 100 makes air cycle machine 10 more effective, as lesscooling air flow is needed to cool bearing 72. This means less coolingair flow needs to be routed away from the main flow path through aircycle machine 10, thus improving the overall efficiency of air cyclemachine 10. Second, as more air is kept in the main flow path throughair cycle machine 10, the heat exchanger has to do less work. This meansthe size and weight of the heat exchanger can be reduced. The improvedefficiency and effectiveness of air cycle machine 10 with heat sink 100outweighs any concerns about the weight or cost of adding heat sink 100to air cycle machine 10. Heat sink 100 greatly improves thethermodynamic performance of air that is flowing through air cyclemachine 10.

While the invention has been described with reference to an exemplaryembodiment(s), it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment(s) disclosed, but that theinvention will include all embodiments falling within the scope of theappended claims.

1. A heat sink that can be positioned around a rotating shaft, the heatsink comprising: a cylindrical body with a first end and a second end; abore running through the body with a first opening at the first end ofthe body and a second opening at the second end of the body; finsextending radially outward from the body and running from the first endto the second end of the body; and channels defined between the fins andthe body and running from the first end to the second end of the body,wherein the channels define hollow air passages that are configured toallow cooling air to flow through them; wherein the body and thechannels are configured to force the cooling air radially outward fromthe rotating shaft and into the channels so that the cooling air flowsthrough the channels and along an inner surface of a bearing.
 2. Theheat sink of claim 1, wherein the body forms a base of each channel thatis positioned radially outward from the rotating shaft.
 3. The heat sinkof claim 1, and further comprising: a first standoff extending axiallyaway from the first end of the body; and a second standoff extendingaxially away from the second end of the body.
 4. The heat sink of claim3, wherein: the first standoff is positioned adjacent to one fin toallow the cooling air to flow across the first end of the body andthrough the channels; and the second standoff is positioned adjacent toone fin to allow the cooling air to flow across the second end of thebody and through the channels.
 5. The heat sink of claim 1, wherein eachof the fins comprise: a contact surface on a radial outer end of thefin, wherein the contact surface is positioned to come into contact withthe inner surface of the bearing to cool the bearing with conductiveheat transfer.
 6. The heat sink of claim 1, wherein the cooling airflows along the inner surface of the bearing to cool the bearing withconvective heat transfer.
 7. The heat sink of claim 1, wherein the boreis sized to receive the rotating shaft.
 8. A rotary machine comprising:a shaft extending through the rotary machine; a bearing positionedaround the shaft; and a heat sink mounted on the shaft between thebearing and the shaft, wherein the heat sink has a cylindrical body withfins extending radially outward from the body and running from a firstend to a second end of the body, and channels between the fins and thebody running from the first end to the second end of the body that arehollow air passages that are configured to allow cooling air to flowthrough them; wherein the body of the heat sink and the channels areconfigured to force the cooling air radially outward from the shaft andinto the channels so that the cooling air flows through the channels andalong an inner surface of the bearing.
 9. The rotary machine of claim 8,wherein the body forms a base of each channel that is positionedradially outward from the rotating shaft.
 10. The rotary machine ofclaim 8, and further comprising at least one of the following: a fansection with a fan blade mounted on the shaft; a compressor section witha compressor nozzle mounted on the shaft; or a turbine section with aturbine nozzle mounted on the shaft.
 11. The rotary machine of claim 8,wherein the bearing is a foil bearing.
 12. The rotary machine of claim8, wherein the heat sink further comprises: a bore running through thebody with a first opening at the first end of the body and a secondopening at the second end of the body, wherein the shaft extends throughthe bore.
 13. The rotary machine of claim 8, wherein each of the finscomprise: a contact surface on a radially outer end of the fin.
 14. Therotary machine of claim 13, wherein the contact surface of each of thefins is positioned against the inner surface of the bearing toconductively cool the bearing.
 15. The rotary machine of claim 8, andfurther comprising: a cavity around the shaft defined by a housing andthe bearing through which cooling air can flow.
 16. The rotary machineof claim 15, wherein the heat sink is positioned in the cavity so thatcooling air that flows through the cavity will also flow through thechannels along the inner surface of the bearing to convectively cool thebearing.
 17. The rotary machine of claim 8, and further comprising: afirst standoff extending axially away from the first end of the body;and a second standoff extending axially away from the second end of thebody; wherein the first standoff and the second standoff are positionedto limit axial movement of the heat sink on the shaft.
 18. The rotarymachine of claim 17, wherein: the first standoff is positioned adjacentto one fin to allow the cooling air to flow across the first end of thebody and through the channels; and the second standoff is positionedadjacent to one fin to allow the cooling air to flow across the secondend of the body and through the channels.